日本海沟俯冲带海底地震动累积能量参数的条件预测模型

Condition prediction model of cumulative energy of seafloor ground motions in the Japan trench subduction zone

阿里亚斯强度(IA)、累积绝对速度(CAV)和峰值地面加速度(PGA)已被广泛用作地震动强度的评价指标.为了研究海底地震动特征及其能量累积效应,采用日本海沟区域的138次浅地壳地震的2605组三分量记录、125次俯冲板内地震的2669组三分量记录和267次俯冲板间地震的5693组三分量记录来建立IA-PGA和CAV-PGA条件模型,并研究其对震级(MW)、震源机制、断层距(Rrup)、海水深度(DW)以及剪切波速(VS)等于1.5 km·s^(-1)的深度(D15)等解释变量的潜在依赖性.基于条件模型,建立了海域的IA和CAV地震动预测方程(GMPE).研究结果表明:各个解释变量对条件模型有着不同影响,震级为主要影响因素;震级对海域的能量累积效应影响较大,随着震级增大,能量累积效应越大.通过基于条件模型得到IA和CAV预测模型与现有陆域的IA和CAV模型进行了比较,在相同震级和距离下,海域的能量累积效应要大于陆域.本文提供了海域的从PGA估算IA、CAV的方法,能用于损伤预测和评估、地震预警(EEW)和海啸预警等.

Arias intensity(IA),cumulative absolute velocity(CAV)and peak ground acceleration(PGA)have been widely used as evaluation indexes of ground motion intensity.To investigate the characteristics of subduction earthquake ground motion and its energy accumulation effect,in this study,2605 sets of three-component records from 138 shallow crustal earthquakes,2669 sets of three-component records from 125 intraslab earthquakes and 5693 sets of three-component records from 267 interface earthquakes were used to establish the IA-PGA and CAV-PGA conditional models.The potential dependence on explanatory variables such as magnitude(MW),focal mechanism,rupture distance(Rrup),seawater depth(DW)and depth at shear wave velocity equal to 1.5 km·s^(-1)(D15)is investigated.Based on the conditional model,the offshore IA and CAV ground motion prediction equation(GMPE)is established.The results show that each explanatory variable has different effects on the conditional model,and magnitude is the main influencing factor.Magnitude has a great influence on the offshore energy accumulation effect,and the energy accumulation effect increases with the increase of magnitude.The IA and CAV prediction models based on the conditional model are compared with the existing onshore IA and CAV models.Under the same magnitude and distance,the offshore energy accumulation effect is larger than that onshore.This paper provides a method for estimating IA and CAV from PGA,which can be used for damage prediction and assessment,earthquake early warning(EEW)and tsunami warning.